Agricultural planters often have a seed tube sensor which counts the seeds being planted. The sensor normally includes a photo-electric cell with a light emitter which generates a light beam, which in turn is sensed by a light receiver. The photo-electric cell for each seed tube is operatively connected to a monitor mounted in the tractor cab. The monitor has lights corresponding to the seed tube sensors. A monitor light for each seed tube sensor is normally on and will momentarily blink off each time the light beam from the photo-electric cell is broken by a seed passing through the seed tube.
When a monitor light remains off during planting, the operator cannot tell if the planter is properly planting seeds. For example, the seed tube may be blocked with chaff or the like such that seeds cannot pass therethrough. Another problem may be that dust has collected within the seed tube so as to prevent the sensor from functioning, but without effecting the passage of seeds through the seed tube. There may also be a problem elsewhere in the electrical system of the tractor, such as a corroded wire or a burned out monitor light. Thus, the problem may be anywhere between the discharge end of the seed tube and the tractor monitor. Such problems make it impossible for the operator to know whether seeds are being properly planted.
Since the photo-electric cell sensor is a key component of the planter system, it is desirable to know whether the photo-electric cell functioning properly when the monitor indicates that a problem exists. The seed tubes cannot be visually checked for blockage. Therefore, it is normally necessary to disassemble the planter and take the sensor and other components, or alternatively to take the entire planter, to a remote service station in order to check the operation of the photo-electric cells. Both of these alternatives are time consuming and therefore undesirable, particularly during the short planting season.
Agricultural combines also may have a sensor which monitors the combine speed. The sensor senses the rotation of a shaft on the combine and generates a signal in response thereto. The signal is transferred to a monitor in the combine or tractor cab which indicates the RPM of the shaft, and thus the combine's speed.
There are two basic types of combine sensors. The first type of sensor, commonly found on John Deere and Massey-Ferguson combines, includes a magnet mounted on the shaft with a spaced apart electronic pickup which generates an electrical impulse as the magnet passes by the pickup during each revolution of the shaft. The second type of sensor, often used on New Holland combines, includes a slotted disk or tooth gear mounted for rotation on the shaft, with a magnet spaced closely to the disk or gear so as to generate an impulse each time a slot or tooth passes by the magnet during the rotation of the shaft.
When the monitor indicates a malfunction, the operator cannot tell if the problem is in the combine, in the sensor, in the monitor, or in the electrical system of the tractor. Such problems make it impossible for the operator to know whether the combine is functioning properly.
Since the combine sensor is the easiest part to physically replace, it is common for a new sensor to be bought and installed. However, if the problem is not in the sensor, time and money have been wasted.
Accordingly, the primary objective of the present invention is the provision of a portable diagnostic device for testing seed tube and/or combine sensors in situ.
Another objective of the present invention is the provision of a portable testing device for checking the operation of seed tube or combine sensor which can be quickly and easily connected to the harness of the sensor.
A further objective of the present invention is the provision of a portable diagnostic device for agricultural implement sensors which is economical to manufacture and easy to use.